Guide bars of this kind are disclosed in U.S. Pat. Nos. 3,581,783 and 4,693,005. The fill body disposed within the guide groove and arranged in the region of the lubricating bore is provided to bridge the gap between the rakers of the drive links and the groove bottom. This gap is present because of manufacturing reasons and assures a jam-free passage of the drive links through the guide groove. The fill body defines an elevated segment of the groove bottom in the region of the lubricating bore so that the supplied lubricant is taken up by the rakers as completely as possible and thereafter is directed to the pivot joints of the saw chain. It is intended to prevent the accumulation of large quantities of lubricant on the groove bottom in this manner which would otherwise be lost for the purpose of lubrication.
In known guide bars, the fill body is configured so that it partially overlaps the lubricating bore within the guide groove whereby the metering of lubricant is made difficult. The fill body disclosed in U.S. Pat. No. 3,581,783 is configured to be convex at its end face directed outwardly whereby the lubricant, which is usually lubricating oil, runs off in the direction toward the groove bottom at both sides of the lubricating bore. In this way, a considerable quantity of the lubricating oil reaches the groove bottom without being grasped by the rakers of the drive links.
U.S. Pat. No. 4,693,005 discloses an embodiment wherein the end face of the fill body which defines the elevated segment of the groove bottom is level and by means of which an improved take-along function of the drive links is achieved. However, because of the very rapid movement of the saw chain, a part of the lubricating oil is nonetheless directed to the groove bottom because the rakers of the drive links displace the lubricating oil on the end face of the fill body directly after the oil exits through the lubricating bore toward the groove bottom.
A further problem in the manufacture of the guide bar is that the depth of the guide groove varies within very large manufacturing tolerances. In contrast thereto, the fill body has the same elevation for all guide bars of the same type because of manufacturing reasons so that in dependence upon the manufacturing tolerances of the guide bar, a more or less large gap exists between the rakers of the drive links and the end face of the fill body defining the elevated segment of the groove bottom. The intended effect of the take-along of lubricating oil is therefore subjected to large variations among guide bars and this effect can become lost in dependence upon the particular guide bar. A gap of a certain width between the raker of the drive link and the end face of the fill body is to be deliberately provided because the drive links dip deeper into the guide groove in dependence upon increasing wear of the side links of the saw chain so that the fill body can then become a restriction for the through-passage of the drive links.